Black Spots on Marigold Seedlings

nutsaboutflowers(2b/3a)April 29, 2010

Well, after failing at my first attempt at starting from seed, I tried again.

Things are going much better this time. However, there's tiny black spots on most of my first true leaves. I'm pretty sure I've seen black spots on Marigolds when I've purchased plants at the greenhouse. Haven't I? Is it O.K.?

Also, I planted two types and unbelievable as it seems, I didn't label them. I would assume that the larger seedlings belong to what will be bigger plants, and the smaller ones belong to the smaller plants, but we all know what assuming does =:) Am I right?

No I've never had black spots on my marigolds and I have no idea what you have if they,ve been grown inside.

Again a no as to size. In the seedling stage it it is hard to tell anything about the eventual size. They are usually all about the same in the seedling stage. A Small marigold that has sprouted before a larger one will be bigger than the larger one. You can only tell when they grow bigger

I am going to attach 2 pictures of my marigold seedlings (taken about 10 days apart). Hopefully you can see in the second picture the little black spots on the leaves (theya re on the tops, but you can see them through the leaves in the picture). These are, to the best of my knowledge, normal coloring for marigolds. At least they have always been on marigolds I have seen (store bought or grown myself).

I don't think some people pay that much attention. My giant marigolds had purple/black spots on all the (for lack of knowledge of plant anatomy) hair follicles if I'm remembering correct. Since it showed no lack of health and vigor I assumed it was normal.

Please read link below. Please make sure you read down to "Recognizing Iron and Manganese Toxicity".
Many seed mixes are peat which can be acid.
Many fertilizers can shift the soil to acid.
Commerical marigold growers often add lime and use specific Nitrogen fertilizers that will not shift the soil to acid.

I couldn't make out the picture for "early signs of toxicity", but I can tell you that my marigolds last year had spots and I was worried about it. I posted about the problem and I got tons of conflicting info.

All I can say is that I still don't know what it was. The spots were perfectly spaced on the leaves and if I had not known better, I would have thought it was the normal design of the leaf.

I kept them quarantined and they all grew up normally, produced normal flowers and did no harm to any plants I planted them next to.

I am still curious as to what it is, but frankly as long as the plant remains healthy, I would assume it is harmless. Of course, if the plant changes colors, yellows, dies or gets stunted etc.....I'd trash them.

I grow marigolds from this company (link below) which are the finest marigolds I have ever grown (their marigolds like Narai and Bali, not the others they also provide.) Click the "Pest Management" tab to a link to their descrption of problems. There are three tabs at the top of that page.

It is funny when I say that I grow marigolds people many times say, Yes, and I hear that marigolds chase pests from the garden. (something like that). You only have to look at the pests that commerical growers face to realize that only a very few ward off pests, like Guardian.